The difference in results can be due to several factors:

Tester settings: If you are testing on ticks, the input data is generated differently each time, which can lead to variations in the results with each test.

Expert Advisor settings: The way your EA reacts to the same market data may vary depending on its internal logic, parameters, or specific conditions set in the strategy.

These factors can cause the same quotations to produce slightly different outcomes on each test run.